Looks like the video is a good source for reference. You already got the likeness down. If you haven’t already, you might want to just check out some of the Cash photos on Corbis.com …not all from that time period but a few.
Here’s a couple:
What have you done to the skin detail dude? It looked awesome. I think it could be saved and played with the forms underneath on a lower subd instead of smoothing it all out.
Im
Thanks for the refs, i haven’t checked that site, in the video he’s a good few years older than the pics you posted and everything seems to have gone south on his face.
I think i’m nearly there, things always look a bit strange without hair an such.
cherub_rock
I still have the skin detail, but i will do it again, i just turned off the layer for the last screen grab.
Here’s a quick clay render, no bump or displacement yet, i just wanted to see how the model would look like rendered with a physically accurate camera.
Lots of adjustments have been made since my last post, i’m happy with the likeness now.
The Last one is pretty good mate ! 
Thanks AR-MAN
Here’s my final render, i decided to go for b&w and use zbrushes renderer.
Looks great!
Here’s a quick pass through xsi mental ray, still got some work to do on the diffuse and spec maps but slowly getting there.
Started to work on the hair, need to add sideburns, eyebrows etc.
